The possibility of incinerating liquid sludge and household refuse in a combined treatment has already been examined. Past efforts introduce sludge cakes exhibiting a sufficient dryness, with household refuse, directly into an incineration furnace. However, such a process has limitations, especially with regard to the proportion of dried sludge in relation to the household refuse and is thus difficult to exploit. Investigations have also been made into processes using a recovery of the heat energy produced by the incineration of household refuse in order to carry out the drying of the sludge which is then incinerated together with the household refuse.